The launch of the Lumia 900 in the US on April 8 has been, so far at least, a huge success for Nokia and for Microsoft's Windows Phone in general. Indeed, the smartphone's carrier AT&T has been having issues with keeping units of the Lumia 900 in stock, with the cyan and white versions being particularly popular with the US audience.

Now there's word that the excellent US sales for the phone have caused the UK launch date for the Lumia 900 to be delayed. The Phones 4U retailer originally announced an April 27th UK launch for the smartphone. Now, as V3.co.uk reports, that launch date has been pushed back a few weeks. The site reports that the Phones4U will now start selling the smartphone on May 14th.

Another UK smartphone outlet, Carphone Warehouse, is also expected to start selling the Lumia 900 sometime in May, although an exact date has yet to be announced. A Nokia spokesperson said, "The overwhelming demand for the Lumia 900 in the US with AT&T has, unfortunately, had a small knock-on effect on product availability in the UK."

Nokia CEO Stephen Elop said last week that sales of the Lumia lineup as a whole "have been mixed", adding that while sales of the phones in the US have exceeded the company's expectations " ... establishing momentum in certain markets including the UK has been more challenging." It will be interesting to see if Nokia has learned from its Lumia 900 US experience and will try to translate that to the UK.